In a remarkably swift descent, Mr. Christie’s endorsement of Donald J. Trump for president, his repeated side-by-side appearances with the real estate mogul and his adoring, 31-minute televised gaze at him on Tuesday night has turned the Republican governor into the subject of unusually biting and intense ridicule.

In an extraordinary show of disgust, six New Jersey newspapers issued a joint editorial calling for Mr. Christie’s resignation on Tuesday, on the same day that the publisher of a major newspaper in New Hampshire took the unusual (and seemingly unnecessary) step of rescinding its previous pledge of support for him as a presidential candidate.

Democratic leaders in New Jersey are discussing ways to cut Mr. Christie’s $175,000 salary, arguing that he is shirking his duties by traveling the country to campaign with Mr. Trump.

And a leading state senator on Wednesday raised the possibility of impeaching Mr. Christie for “dereliction of duty.”

“We thought, with his White House quest over, he’d come home,” said the senator, Loretta Weinberg, a Democrat from Teaneck. “But I guess for the next three months he’s going to travel around the country selling the splendors of Donald Trump.”

Perhaps most painfully for a governor who prizes his reputation as unbossable and independent. Mr. Christie has inspired a cornucopia of online parodies skewering his relationship with Mr. Trump as a form of political servitude.

“Why,” Dan Savage, the liberal writer, wondered on Twitter, “hasn’t President Obama sent the Navy SEALs in to rescue Chris Christie already?”

Mr. Christie appeared onstage at Mr. Trump’s Mar-a-Lago resort in Palm Beach, Fla., on Tuesday, as his warm-up act and head-nodding affirmer. Seemingly minutes later, carefully cut videos started zinging around the Internet, analyzing every movement of Mr. Christie’s eyes, head and fingers for signs of duress, as if he were a prisoner of war.

The image of Mr. Christie as a supplicant proved irresistible. Longtime enemies and disapproving predecessors could not pass up the chance to weigh in.

“They were very strange expressions — or nonfacial expressions on his face,” said Christie Whitman, a former Republican governor of New Jersey and a skeptic of its current leader. She summoned a soupçon of faint praise. “That’s hard to do for a long period of time.”

Senator Weinberg, a Christie nemesis who watched the news conference from home on Tuesday night, could not pull herself away.

“It almost did me in,” she said. “I found it unpleasant, disconcerting and ....”

She paused. “I am trying to think of negative words that are still appropriate to use.”

She settled on “really awful.”

Those close to Mr. Christie said he anticipated the furor of his endorsement, but has been a bit taken aback by the depth of the vitriol over the past few days. In his mind, linking arms with Mr. Trump was practical, loyal and politically savvy, in keeping with his decision, in 2011, to become the first major Republican official to endorse Mitt Romney, who ultimately became the nominee.

Privately, they said, Mr. Christie and his team attribute the anger to the feeling of helplessness that once-powerful Republican leaders feel over Mr. Trump’s ascent, something those leaders did little to stop and now want to pin, perhaps unfairly, on the governor.

“I went into this with my eyes wide open; I knew it would make some people upset,” Mr. Christie said during his monthly radio show on Monday.

Hinting at his frustration with Republicans who have second-guessed him but stayed out of the campaign, he added: “I’m not an on-the-sidelines guy. I’m not going to be one of these people who sits on the side and snipes.”

But Mr. Christie’s enthusiasm for politics means traveling out of state, an expensive habit many expected the governor to curtail after he quit the presidential campaign a few weeks ago.

According to The Star Ledger of New Jersey, Mr. Christie has spent all or part of 520 days outside the state since the beginning of 2013. The trips, collectively, cost hundreds of thousands of dollars in flights, meals and lodging for the governor’s 24-hour security detail, which is typically four to six people, Ms. Weinberg said.

All of it, she said, is footed by New Jersey taxpayers.

“He’s costing us a heck of a lot of money,” Ms. Weinberg said.

Mrs. Whitman said it was time for Mr. Christie to come home.

“You have to do the job you’ve got,” she said, adding, “You can’t you do it from Florida.”

The workaday drudgery that awaits Mr. Christie in New Jersey, however, may not lead him to the same conclusion.

He could travel the country aboard Mr. Trump’s private plane or he could contend with Democratic lawmakers who are rejecting his appointment of a justice to the State Supreme Court. He could give rousing speeches about making America great again, or he could absorb a new poll that shows hisapproval rating is at 30 percent in New Jersey, the lowest since he took office. He could advise Mr. Trump on strategy, or he could watch as a Democrat who may seek to replace him as governor circulates a petition demanding that Mr. Christie make a choice.

“Either Governor Christie comes home and performs the job for which we continue to pay him or he needs to get out of the way,” the petition reads.

Its author, Philip D. Murphy, a former ambassador to Germany, said the response was overwhelming. Within hours of its creation, more than 5,000 people had signed it.